Systems and methods for proprioceptive stimulation to prevent unintentional falls

ABSTRACT

Systems, devices, and methods are provided for reducing a risk of unintentional falls in a subject that is at risk for falls. The device includes a sensor and a stimulator. The sensor is configured to be positioned adjacent a body portion of the user that changes orientation when the user sits and stands. The sensor is also configured to emit an activation signal when the user stands and to emit a deactivation signal when the user sits or lies down. The stimulator is in communication with the sensor and is configured to be positioned adjacent one of a calf and a lower back of the user. The stimulator is configured to vibrate at a frequency that stimulates proprioceptors of the user without inducing muscle contractions upon receipt of the activation signal from the sensor and to cease vibration upon receipt of the deactivation signal from the sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/469,496, filed Jun. 13, 2019, which represents the U.S.National Stage of International Application No. PCT/US2017/067545 filedDec. 20, 2017, which claims the benefit of U.S. Provisional PatentApplication No. 62/436,559 filed on Dec. 20, 2016, the entire contentsof which are incorporated herein by reference.

FIELD

Embodiments of the present disclosure are generally directed to systems,methods, and devices for proprioceptive stimulation to prevent and/orreduce the risk of unintentional falls, for example, in subjects at anincreased risk of falls.

BACKGROUND

Aging is related to reductions in physical function, contributing toinactivity, frailty, and incident falls. More specifically, seniorpersons generally experience a decline in their ability to flawlesslyexecute a complex skill for body equilibrium during standing andwalking. This skill of maintaining equilibrium, which is learned andperfected through the first several years of human life, is based onfine tuning the activity of numerous components of the neuromuscularsystem. With increasing age, the efficiency of these components declinesand, in turn, system function deteriorates. Muscles lose their mass,strength, and power, which is known as sarcopenia and dynopenia.Proprioceptors, muscle spindles, and tendon organs, which detect musclelength and force, degenerate and their numbers reduce. The amount ofneural fibers innervating muscles declines, and the velocity of signaltransmissions via surviving neural fibers reduces due todemyelinization. Additionally, with respect to the brain, the graymatter of the cerebral cortex, the thalamus, and the cerebellum shrinksand reduces in volume at a rate of about 5 cm{circumflex over ( )}3 peryear, while the volume of white matter, consisting of neuronal fibersconnecting different parts of the brain and spinal cord, also becomessmaller.

The first manifestation of age-related deterioration of body equilibriumis an increase in body sway during standing. As an increased magnitudeof body movement can increase posture instability, elders can eventuallylose their balance and fall, suffering bone fractures, jointdislocations, concussions, and even death. For example, every year, anestimated 30-40% of elders over the age of 65 may fall at least once,and such falls lead to injuries, loss of independence, or death in about33% of those who fall. Given the serious impact of falls on the elderlypopulation, there is a need for devices and methods to improve balanceand decrease fall risk.

SUMMARY

Embodiments of the present disclosure provide systems, devices, andmethods for reducing a risk of unintentional falls in a subject at riskfor falls. For example, some embodiments include a device comprising atleast one stimulator supported by a first support member and at leastone sensor supported by a second support member. The device can beconfigured and arranged so that the at least one sensor is in operativecommunication with the at least one stimulator. Moreover, the at leastone sensor can activate the stimulator when a user is in a substantiallystanding position and deactivate the stimulator when the user in asubstantially seated position. In some embodiments, the stimulator canbe configured to stimulate proprioceptors of the user at a frequencythat does not induce muscle contractions.

In one aspect, a device for providing proprioceptive stimulation to auser is provided. The device includes a first support member, a secondsupport member, a stimulator, and a sensor. The first support member andthe second support member are each configured to be worn by the user.The stimulator is at least partially supported by the first supportmember and is configured to stimulate proprioceptors of the user at avibration frequency that does not induce muscle contraction. The sensoris at least partially supported by the second support member and isconfigured to control operation of the stimulator based on anorientation of the user.

In another aspect, a method of reducing a risk of unintentional falls ina user is provided. The method includes a device configured to be wornby the user, including a stimulator configured to be positioned adjacenta body portion of the user and a sensor configured to be positionedadjacent to an upper leg of the user. The sensor is in communicationwith the stimulator and is configured to provide an activation signalwhen the user is in a substantially standing position. The method alsoincludes donning the device by the user, and activating the stimulatorvia the activation signal from the sensor when the user is in thesubstantially standing position. Activating the stimulator according tothe present method causes the stimulator to vibrate against the bodyportion of the user at a frequency that stimulates proprioceptors of theuser.

In yet another aspect, a device for providing proprioceptive stimulationto a user is provided. The device includes a sensor and a stimulator.The sensor is configured to be positioned adjacent a body portion of theuser that changes orientation when the user sits and stands. The sensoris also configured to emit an activation signal when the user stands andto emit a deactivation signal when the user sits or lies down. Thestimulator is in communication with the sensor and is configured to bepositioned adjacent one of a calf and a lower back of the user. Thestimulator is configured to vibrate at a frequency that stimulatesproprioceptors of the user without inducing muscle contractions uponreceipt of the activation signal from the sensor and to cease vibrationupon receipt of the deactivation signal from the sensor.

Additional objectives, advantages and novel features will be set forthin the description which follows or will become apparent to thoseskilled in the art upon examination of the drawings and detaileddescription which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a device according to someembodiments.

FIGS. 2A and 2B are schematic illustrations of the device of FIG. 1donned by a user, where FIG. 2A depicts the user wearing the devicewhile in a seated position and FIG. 2B depicts the user wearing thedevice while in a standing position.

FIG. 3 is a flow chart illustrating a method, according to someembodiments, of reducing a risk of unintentional falls and/or enhancingbalance.

FIGS. 4A and 4B are graphs illustrating results of a study conducted toassess the efficacy of embodiments of the device to provideproprioceptive stimulation to enhance balance and reduce the risk ofunintentional falls in young subjects and elderly subjects, where FIG.4A illustrates changes in Center of Mass (COM) range during standingwith 30 Hz proprioceptive stimulation as a function of COM range duringstanding without proprioceptive stimulation in young subjects, and FIG.4B illustrates changes in COM range during standing with 30 Hzproprioceptive stimulation as a function of COM range during standingwithout proprioceptive stimulation in elderly subjects.

FIGS. 5A-5F are graphs illustrating results of a study conducted toassess the efficacy of embodiments of the device to provideproprioceptive stimulation to enhance balance and reduce the risk ofunintentional falls in healthy young subjects (HY), healthy elderlysubjects (HE), and elderly subjects with fall risk (FR), where FIGS. 5A,5B, and 5C are bar graphs illustrating average COM sway without and withproprioceptive vibration for the HY group, the HE group, and the FRgroup, respectively, and FIGS. 5D, 5E, and 5F are graphs illustratingCOM sway during proprioceptive vibration as a function of baseline(i.e., no vibration) COM sway for the HY group, the HE group, and the FRgroup, respectively.

Corresponding reference characters indicate corresponding elements amongthe view of the drawings. The headings used in the figures should not beinterpreted to limit the scope of the claims.

DETAILED DESCRIPTION

Given the serious impact of falls on the elderly population, there is aneed for strategies to improve balance and decrease fall risk. Apotentially efficient strategy may be developed based on enhancing weaksignals via background near-threshold noise in sensory and motorsystems, known as stochastic resonance. Prior work has shown thatlow-level stochastic stimulation elicited by vibration of soles of thefeet and electrical pulses applied to the knee can enhance the posturalperformance of elderly people. The present disclosure provides systemsand methods that translate these finding into real-world solutions toaid in reducing the risk of unintentional falls.

More specifically, some embodiments provide a device and methods fordelivering proprioceptive stimulation to an individual, user, subject,or patient (hereinafter, termed “user”). The device can be configured toreduce the risk of and/or prevent unintentional losses of balance forusers in need thereof. For example, the device can be employed by anyuser (e.g., regardless of age, gender, sex, etc.) that suffers fromreduced balance and/or experiences an increased likelihood of sufferingfrom an unintentional fall or loss of balance.

Accordingly, some embodiments can improve a user's balance bystimulating one or more biological tissues to enhance balance and/or tosubstantially reduce or prevent the risk of unintentional falls. Withoutbeing necessarily bound by any theory, some embodiments of the deviceand methods herein are based on the following information andprinciples.

Generally, the magnitude of body sway in a user depends on detection andprocessing of signals in somatosensory, visual, and vestibular systemsinvolved in maintenance of balance. A first postural response formaintaining balance in a user can be a motor activity known as the anklestrategy, which foremost involves activation of muscles crossing theankle joint, such as the gastrocnemius and the tibialis anterior. Forexample, while in a substantially vertical position (e.g., standing),small angular deviations occur in the ankle joint. These deviations canresult in a change in length of attached muscles, which can be detectedby proprioceptors (i.e., muscle spindles). Signals from proprioceptorscan then be directed to motor neurons, which activate the parent musclesto restore joint position (that is, to counteract the deviations).Noteworthy, postural responses are not limited to activation of theankle muscles but can involve activation of other anti-gravitationalmuscles crossing the knee and the hip, such as the quadriceps musclegroup, the biceps femoris, and any other muscle of the leg, as well asabdominal and spine muscles.

As a user ages, the efficiency of this response loop declines. Morespecifically, with age, the sensitivity of sensory systems degrades andmotor neurons become less responsive to changes in sensory signals. Thesubject's neuromuscular system is, thus, more apt to making mistakes(e.g., by not sensing deviations or not correctly responding to senseddeviations in posture), which can cause loss of balance and/orunintentional falls.

It is suggested that the deterioration of signal processing in sensoryand motor systems, to some extent, can be compensated by applyingauxiliary random low-intensity stimulation, which produces the effect ofstochastic resonance. Indeed, an application of such stochasticresonance to a division of the somatosensory system responsible forcutaneous sensation has been shown to enhance postural stability duringboth standing and walking. Sole vibrations with random frequencies andmagnitude (below a threshold for producing perception) for activatingplantar mechanoreceptors have been shown to improve balance and gait inhealthy elderly people. Also, an increased body sway in patients withdiabetic neuropathy and stroke was reduced using subsensory mechanicalnoise applied to soles of feet. Stimulation with a low-level electricalnoise applied at the knee, which presumably activated cutaneousreceptors, was found to enhance balance performance in healthy elderlypersons. At the same time, consequences of low-intensity stimulation onanother division of the somatosensory system, which is responsible forsensation of muscle and tendon length and force, are not well understoodyet. It is known that vibration of bellies or tendons of ankle muscles,which are important for maintenance of balance during biped standing inhumans, elicit sway of the body. The magnitude of sway depends on thefrequency of vibration. In healthy persons, the maximal postural effectis produced by 80-100 Hz vibrations; it diminishes with a decrease infrequency, and is not visible with vibrations with frequencies below30-40 Hz.

According to some embodiments of the present disclosure, to compensatefor the above-described decline, stochastic resonance can be induced inthe proprioceptive loop with a substantially or completely continuousnear-threshold stimulation of muscle proprioceptors. The near-thresholdstimulation of proprioceptors may comprise relatively low-frequencyvibrations exerted on some portions of the body of the user (e.g., by adevice). For example, the near-threshold stimulation can be deployed aslow-frequency vibration applied to a portion of a user's leg, such asthe lower leg or, more specifically, areas of the shin, which producesstimulation of receptors of the gastrocnemius or “calf” muscle.Alternatively or additionally, the near-threshold stimulation can bedeployed as low-frequency vibration applied to a portion of a user'slower back. By way of example, the low frequency vibration can causerepetitive stretching of the adjacent muscle, which may be sufficientenough movement to be detected by the proprioceptors, which then sendcorresponding signals to the motor neurons. These signals can elevate anexcitability of the motor neurons and increase the probability ofgenerating action potentials, which trigger muscle contractions,changing joint position. In other words, the low frequency vibration mayincrease the responsiveness of motor neurons to proprioceptive stimuliproduced by the natural sway of the body and, thus, facilitatecompensatory movements of the body necessary for the maintenance ofbalance.

Accordingly, the applied low-frequency stimulation can produceresonance-type responses in the proprioceptive loop, which canfacilitate motor responses to perturbations in posture. Put another way,embodiments described herein can provide users with low frequencystimulation of proprioceptors, which can then lead to improved responsesin the aforementioned response loop. These improved responses can helpto achieve needed changes in posture, thereby reducing a likelihood ofexperiencing an unintentional loss of balance and/or suffering anunintentional fall.

As used herein, the term “threshold stimulation” may be considered asthe minimum frequency of vibratory stimulation at which the vibration isconsciously perceived by the user. As such, “near-threshold stimulation”may be considered as the stimulation that is substantially close to(e.g., above or below) the threshold stimulation and therefore mayinclude a window or range comprising subthreshold, threshold, and/orabove-threshold stimulation frequencies. In some embodiments, thenear-threshold stimulation may comprise relatively low-frequencyvibrations, such as less than about 40 Hz. In further embodiments, thenear-threshold stimulation may comprise relatively low-frequencyvibrations, such as between about 20 Hz and about 40 Hz. Notably, anexact threshold stimulation may be different for each user depending onthe user's age and/or other characteristics. For example, for someusers, threshold may be about 30 Hz, while 40 Hz may be just abovethreshold. However, as further described below, other frequencies may becontemplated within the scope of this disclosure.

Moreover, it is believed that vibratory stimulation of a muscle with arelatively low frequency (e.g., approximately 40 Hz or a lowerfrequency) can stimulate proprioceptors, but may not result in anysignificant motor responses. Put another way, stimulation ofproprioceptors at a relatively low frequency (e.g., approximately 40 Hzor below) can induce improved responses to perturbations in posture, butmay not induce any significant motor responses, such as musclecontractions.

Accordingly, by applying the device and methods described herein, a usermay experience improved balance and reduced risk of loss of balanceand/or reduced risk of unintentional falls, which can be attributable toenhancement of proprioceptor sensitivity and potentiation ofmonosynaptic responses of motor neurons by noise-signals elicited bylow-amplitude vibratory stimulation (e.g., stretches) of a parentmuscle.

Referring now to FIG. 1, a device 10 is provided for deliveringproprioceptive stimulation to a user, in accordance with someembodiments, to reduce the risk of and/or prevent unintentional lossesof balance. The device 10 can be employed by any user (e.g., regardlessof age, gender, sex, etc.). Furthermore, the device 10 can be employedby a user that may, for example, require or otherwise need and/or wishto use the device 10 to reduce the risk of loss of balance and/or reducethe risk of unintentional falls. Put another way, embodiments of thedevice 10 may provide additional improvement for users that experience areduction in the ability to maintain balance and perturbations ofposture (e.g., compared to others that generally do not experience suchlosses or perturbations).

As illustrated in FIG. 1, the device 10 can be configured to engageand/or be worn (i.e., donned) by the user and can include one or moreelements that, together, can provide the aforementioned benefits. Forexample, in some embodiments, the device 10 can comprise a first supportmember 12, a second support member 14, a sensor 16, a stimulator 18, anda power supply 20.

In some embodiments, the first and second support members 12, 14 can beconfigured to be coupled to or worn by the user. As such, when a userwishes to employ the device 10, the user can employ the first and secondmembers 12, 14 to don the device 10. For example, in some embodiments,the first support member 12 and/or the second support member 14 can eachcomprise a generally cuff-like structure configured to wrap around aportion of the user's body, and comprise configurations such as, but notlimited to, a sleeve, a wrap, a strap, a band, or another suitablestructure. Furthermore, in some embodiments, the first support member 12and/or the second support member 14 can each comprise a generallycontinuous and flexible structure that can expand and contract upon theuser donning and doffing the device 10 (such as a flexible cuff-likestructure). Additionally or alternatively, the members 12, 14 cancomprise a cuff-like portion and a separate flexible portion capable ofexpanding and contracting (such as, but not limited to, a fabric sleeveand an attached elastic band).

Additionally, in embodiments where the first support member 12 and/orthe second support member 14 do not form a continuous loop, the member12, 14 can include a fastening structure, such as Velcro®, one or moresnaps, one or more buttons, or other suitable fasteners configured to beengaged when the user dons the member 12, 14 in order support the member12, 14 in a position relative to the user. Alternatively, or inaddition, the member 12, 14 can comprise a structure similar to a beltsuch that the member 12, 14 can be cinched around a portion of the user.Accordingly, the member 12, 14 can be wrapped around a portion of theuser and fastened to itself via one of the fastening methods describedabove.

It should be noted that, while the first and second support members 12,14 are collectively described above, they need not include the sameproperties or fastening structures and, in some embodiments, maycomprise different structures than each other, or different structuresnot specifically described herein.

With respect to the first support member 12, in some embodiments, thefirst support member 12 can be configured to be worn by the user in alocation so that the device 10 can provide proprioceptive stimulation tothe user. In other words, the first support member 12 can be generallyconfigured to engage one or more portions of the user's body to providestimulation of proprioceptors of the one or more portions. For example,in some embodiments, the first support member 12 can be configured to beworn by the user on a lower portion of the user's body, such as adjacentto the user's waist and/or lower back (e.g., generally similar to abelt). In another example, the first support member 12 can be configuredto be worn on or around a portion of the user's leg, such as a lowerportion or an upper portion of the leg (e.g., as defined by a knee ofthe user, with the upper portion being above the knee and more proximateto the waist of the user and the lower portion being below the knee andmore distal to the waist of the user). In a specific example, the firstsupport member 12 can be configured to be worn on or around a portion ofthe user's lower leg and, more specifically, can be configured to engagethe calf/shin area of the user.

With respect to the second support member 14, in some embodiments, thesecond support member 14 can be configured to be worn by the user toengage one or more portions of the user's body that change orientationbased on the user's activity, as further described below. For example,the second support member 14 can be configured to be worn adjacent toand/or engage an upper or proximal portion of the user's leg, such asthe user's thigh (e.g., generally similar to a garter belt).

FIGS. 2A and 2B illustrate example locations of the first support member12 and the second support member 14 donned by a user. As shown in FIGS.2A and 2B, the first support member 12 is a cuff- or wrap-like structureconfigured to be worn adjacent to a region of the lower leg immediatelydistal to the knee (e.g., adjacent to the shin of the user). Morespecifically, the first support member 12 is configured to be worn toplace at least portions of the device 10 immediately adjacent to thegastrocnemius (i.e., calf muscle) of the user. As further shown in FIGS.2A and 2B, the second support member 14 is a cuff- or wrap-likestructure configured to be worn adjacent to a region of the upper legproximal to the knee (e.g., adjacent to the mid or lower thigh of theuser). Additionally, in some embodiments, as shown in FIGS. 2A and 2B,the device 10 can include two first support members 12 and two secondsupport members 14, where a first support member 12 and a second supportmember 14 can be worn on each leg of the user.

As noted above, in some embodiments, the device 10 can include a sensor16. Generally, the sensor 16 can be configured to sense the user'sorientation, that is, whether the user is standing (or engaging inmovement, such as walking, running, jogging, etc.) or sitting (or lyingdown). For example, the sensor 16 can be coupled to, supported by, ordisposed within the second support member 14, such as within a loop orpocket (not shown) defined by the second support member 14 and sized toreceive the sensor 16. Moreover, in some embodiments, the second supportmember 14 can support a plurality of sensors 16 (not shown).Furthermore, in some embodiments, the sensor(s) 16 can be removable fromthe second support member 14.

As described above, in some embodiments, the second support member 14can be configured to be donned on a user's thigh. As such, the sensor 16can be configured to be positioned at the front, side, or rear of theuser's thigh. Notably, when the user stands or walks, the user's thighis in a substantially vertical position and, when the user sits or liesdown, the user's thigh is in a substantially horizontal position. As aresult, the sensor 16 can be configured to detect or sense this changebetween vertical and horizontal orientations.

Accordingly, in some embodiments, the sensor 16 can be configured as agravitational sensor or accelerometer capable of emitting differentsignals based on the user's orientation. For example, when the sensor 16is oriented one way (e.g., when the user is standing and the thigh issubstantially vertical), the sensor 16 can emit a first signal (such asan activation signal), and when the sensor 16 is oriented another way(e.g., when the user is sitting and the thigh is substantiallyhorizontal), the sensor 16 can emit a second signal (such as adeactivation signal, which may be, in some applications, a zero or opensignal). In one specific example, the sensor 16 can be a gravitationalsensor that initiates a connection (e.g., thereby closing a circuit)when in one orientation and opens the connection (e.g., thereby openingthe circuit) when in another orientation. Thus, in this example, thesensor 16 can provide a high signal (e.g., the activation signal) viathe closed circuit when in one orientation and no signal (e.g., thedeactivation signal) via the open circuit when in another orientation.

It should be noted that, while the sensor 16 is described herein asemitting first and second signals, it is within the scope of thisdisclosure to include sensors 16 capable of emitting more than twosignals. Furthermore, in other embodiments, the sensor 16 can beconfigured and arranged as another structure or device configured toprovide activation and/or deactivation signals. For example, the sensor16 may comprise a chip with or without an integrated circuit and/or anyother structure that can be used to provide activation and deactivationinstructions.

Generally, the sensor 16 can be arranged relative to the user so thatthe device 10 can be at least partially controlled by the sensor 16based on the user's orientation. More specifically, the sensor 16 can beused to provide control over activities of the device 10, that is, toprovide control of proprioceptive stimulation, depending on the user'sorientation. As further described below, the sensor 16 can provide suchcontrol by selectively activating and/or deactivating the stimulator 18.

More specifically, as noted above, the device 10 can include at leastone stimulator 18. The stimulator 18 can be at least partially supportedby, disposed within, and/or coupled to the first support member 12. Forexample, in some embodiments, the stimulator 18 can be disposed within arecess or pocket substantially defined by the first support member 12(and sized to receive the stimulator 18). Moreover, in some embodiments,the stimulator 18 can be disposed within the recess or pocket of thefirst support member 12 so that the stimulator is substantially orcompletely retained in place during operation of the device 10. As such,in one embodiment, the stimulator 18 can be configured to be positionedwithin the first support member 12 so that, when donned by the user, thestimulator 16 is positioned above the belli of the gastrocnemius muscle.Additionally, in some embodiments, the first support member 12 cansupport and/or be coupled to a plurality of stimulators 18. Furthermore,in some embodiments, the stimulator(s) 18 can be removable from thefirst support member 12.

Generally, the stimulator 18 can be any type of device capable ofproviding vibratory stimulation to proprioceptors of the user at arelatively low frequency. In some aspects, the frequency is less thanabout 100 Hz, less than about 90 Hz, less than about 80 Hz, less thanabout 70 Hz, less than about 60 Hz, less than about 50 Hz, less thanabout 40 Hz, less than about 30 Hz, less than about 20 Hz, or less thanabout 10 Hz. In some embodiments, the frequency is about 40 Hz, about 30Hz, about 20 Hz, about 10 Hz, or any frequency in between about 100 Hzand about 10 Hz, between about 40 Hz and about 10 Hz, or between about40 Hz and about 20 Hz. In some embodiments, the frequency may be fixed;however, in other embodiments, the frequency may be adjustable, asfurther described below.

In some embodiments, the stimulator 18 can be configured as an eccentricmotor. In further embodiments, the eccentric motor can be configured asan eccentric rotating mass vibration motor. In one specific example, thestimulator 18 can be a direct drive motor with an attached eccentricload, for example, enclosed in a barrel and capable of sufficientamplitude of movement during vibration (in one application, a1-millimeter amplitude is sufficient; however, other amplitudes may besufficient in other applications). In other embodiments, the stimulator18 can be a linear motor. In such embodiments, the linear motors may beemployed or mounted flush against the portion of the user's body (e.g.,may be held in place against the portion of the user's body via thepocket or loop of the first support member 12, as described above, maybe held in place directly against a portion of the user's body via asupport member 12 in the form of an elastic band or wrap, may be held inplace directly against a portion of user's body via a support member 12in the form of tape secured to the user's body, or may be positioned inother suitable ways).

To the extent that the first support member 12 and the stimulator 18 aredisposed substantially adjacent to the lower leg, the vibrationalmovement of the stimulator 18 can provide proprioceptive stimulation toa portion of the lower leg, such as the gastrocnemius. In otherembodiments, the stimulator 18 or one or more of the plurality ofstimulators 18 can comprise any other structure and configuration thatis capable of providing proprioceptive stimulation to muscle spindles ofthe user to aid the user in maintaining and/or improving balance and/orreducing the risk of unintentional falls. As described above, in someembodiments, the stimulator 18 can provide proprioceptive stimulationwithout inducing muscle contractions or otherwise activating muscles.For example, the proprioceptive stimulation can be provided with arelatively low-level frequency (e.g., approximately 40 Hz or under) toinduce proprioceptive stimulation, but not trigger muscle contractions.By failing to induce muscle contractions, the device 10 enhances balancethrough proprioceptive stimulation, but will not cause the user thephysical and psychological discomfort of ongoing muscle contractions.

In some embodiments, the stimulator 18 can be activated and deactivatedby a power button 22 (optionally shown in FIG. 1) positioned at anylocation on the device 10, such as on the first support member 12.Additionally, in some embodiments, the stimulator 18 can be activatedand deactivated by the sensor 16. More specifically, the sensor 16 canbe configured to provide operative communications (e.g., activation anddeactivation signals) to the stimulator 18. For example, the stimulator18 can receive the activation signal from the sensor 16 to initiatemovement (e.g., vibrational movement) of the stimulator 18. Thestimulator 18 and the sensor 16 can communicate via a wired connection24, as shown in FIGS. 1-2B, or via a wireless communication (such as,but not limited to, a Bluetooth® connection or any other suitablewireless communication technologies).

In some embodiments, the stimulator 18 can be activated and deactivatedby the sensor 16 based on the orientation of the user. Morespecifically, proprioceptive stimulation and balance control may only benecessary while the user is standing. As a result, the sensor 16 can beemployed such that a change of orientation (e.g., moving from sitting tostanding or vice versa) can provide a change in the activation state ofthe stimulator 18. For example, the sensor 16 and the second supportmember 14 can be donned by the user generally adjacent to the mid-thigh,as described above, so that when the user stands or the user's thigh isdisposed in a substantially vertical position, the sensor 16 provides anactivation signal to the at least one stimulator 18 to providestimulation to proprioceptors. Moreover, when the user sits or theuser's thigh is disposed in a substantially horizontal position, thesensor 16 provides a deactivation signal to the stimulator 18 tosubstantially or completely cease providing stimulation toproprioceptors.

In some embodiments, some or all of the stimulators 18 may be configuredto operate in unison upon receiving an activation or deactivation signalfrom the sensor 16. In other aspects, some or all of the stimulators 18may operate on different activation and deactivation signals from thesensor 16 (or sensors 16) such that not all of the plurality ofstimulators 18 operate at the same time and/or provide the same level ofproprioceptive stimulation.

In some embodiments, in addition to or alternative to the power button,the device 10 can include one or more switches, knobs, or dials 26(optionally shown in FIG. 1) configured to control the vibrationfrequency of the stimulator 18 based on user input. For example, in oneembodiment, the device 10 can include one or more switches 26 configuredto adjust the vibration frequency of the stimulator 18 to one or moreset frequencies, such as about 20 Hz, about 30 Hz, about 40 Hz, and/orother frequencies. In some embodiments, the adjustments may be at setintervals, such as 1 Hz, 5 Hz, 10 Hz, or other intervals. For example,in some embodiments, the one or more switches 26 can be used to adjustthe vibration frequency based on the user's personal sensitivity to thevibrations (e.g., based on the user's specific threshold level). Uponsuch adjustments, the stimulator 18 can vibrate at that frequency whenactivated. In some embodiments, the device 10 can include a controller(not shown) in communication with the switch 26 and the stimulator 18and can be configured to interpret user input via the switch 26 tocontrol the frequency of the stimulator 18. However, in otherembodiments, no controller is needed and the switch 26 may be inoperative communication with the stimulator 18 to control the outputfrequency of the stimulator 18. Additionally, in some embodiments, theswitch 26 can be positioned at any location on the device 10, such as onthe first support member 12, as shown in FIG. 1.

Furthermore, as noted above, the device 10 can include a power supply20. The power supply 20 can be operatively coupled to and used to power,for example, the stimulator 18 and/or the sensor 16. For example, asshown in FIG. 1, the power supply 20 can be operatively coupled to thestimulator 18 via a connector 28. Additionally, in some embodiments, thepower supply 20 can be in communication with the power button 22, theswitch 26, and/or the controller. In some embodiments, the power supply20 can be configured as a battery (e.g., a primary cell ornon-rechargeable battery or a secondary cell or rechargeable battery),such as an alkaline battery, a lithium ion battery, a nickel-cadmiumbattery, or another suitable power source.

In some embodiments, the power supply 20 can also be disposed within,coupled to, and/or supported by the first support member 12, as shown inFIG. 1. For example, in some embodiments, the power supply 20 can bedisposed substantially adjacent to the stimulator 18 within the firstsupport member 12, as shown in FIGS. 1-2B. In other embodiments, thepower supply 20 can be supported by the second support member 14 and/ormay be otherwise worn by the user.

In some aspects, with respect to a circuit arrangement, the power supply20 can be disposed between the stimulator 18 and the sensor 16 (and/orbetween the stimulator 18 and the switch 26). As such, the sensor 16 canbe in communication with power supply 20 (e.g., via wired communication24, as shown in FIG. 1, or wireless communication) and/or the stimulator18. In some embodiments, the sensor 16 may be in direct operativecommunication with the power supply 20 and indirect operativecommunication with the stimulator 18. For example, the sensor 16 canprovide an activation signal to the power supply 20, causing the powersupply 20 to provide current to the stimulator 18 to initiate generationof proprioceptive stimulation (that is, initiate the stimulator 18 tovibrate). Conversely, the sensor 16 can provide a deactivation signal tothe power supply 20, causing the power supply 20 to decrease oreliminate the current flowing to the stimulator 18 to reduce oreliminate generation of proprioceptive stimulation (that is, to stopvibration of the stimulator 18). For example, the sensor 16 can act toclose a circuit between the power supply 20 and the stimulator 18 whenin one orientation, and can open the circuit when in anotherorientation.

In light of the above, following paragraph includes a general andexemplary illustration of how a user may employ some embodiments of thedevice 10. The following example is intended for illustrative purposesand use of the device 10 in other manners may be contemplated within thescope of this disclosure.

For example, the device 10 may be employed by initially donning thedevice 10 (e.g., over or under clothing of the user). The second supportmember 14 can be worn on a lower or mid-thigh of the user so that thesensor 16 is able to distinguish when the user's thigh is in asubstantially horizontal position (e.g., seated or lying down) or in asubstantially vertical position (e.g., standing or walking). Inaddition, the first support member 12 can be worn and positioned so thatthe stimulator 18 is substantially adjacent to the gastrocnemius or backof the user. After being donned, the sensor 16 can be used to activatethe device 10 (e.g., by activating the power supply 20 to providecurrent to the stimulator 18) when the user is standing. As such, thestimulator 18 is activated and provides proprioceptive stimulation tothe gastrocnemius (or lower back) of the user to provide theaforementioned benefits. Upon the user returning to a seated position,the sensor 16 provides a deactivation signal to the power supply 20,which then ceases providing current to the stimulator 18, thereby endingproprioceptive stimulation. As such, the device 10 is able to provideproprioceptive stimulation only when the user is at risk for losingbalancing and experiencing an unintentional fall (i.e., when standing).Illustratively, FIG. 2A depicts the user seated such that the device 10is in a deactivated state and FIG. 2B depicts the user standing suchthat the device 10 is in an activated state.

In light of the above example, FIG. 3 illustrates a method 30, accordingto some embodiments, of reducing a risk of unintentional falls and/ormaintaining balance. As shown in FIG. 3, the method 30 includes a userdonning the device at step 32. At step 34, an orientation determinationis made, for example, based on the sensor 16. If, at step 34, the sensor16 senses that the user is sitting, the stimulator 18 is deactivated atstep 36. If, at step 34, the sensor 16 senses that the user is standing(or walking), the stimulator 18 is activated at step 38. In someapplications, steps 32-38 may be repeated until the user takes off thedevice 10 and/or until the user turns off the device 10, for example,via the power button 22.

The following paragraphs provide a discussion of methodologies andresults connected with analyses of some embodiments of theaforementioned device 10. The following paragraphs are not intended tolimit the instant disclosure in any manner.

In particular, according to a first study, postural stability wasexamined in 10 young subjects (YS, 23±2 years) and 19 old subjects (OS,78±9 years), with 10 OS having a history of falls. The device 10 waspositioned as illustrated in FIGS. 2A and 2B. Proprioceptive stimulationwas produced by 30 Hz frequency vibration using the stimulator 18 (i.e.,an eccentric motor) enclosed in the first support member 12 (e.g., asleeve) and positioned adjacent to the gastrocnemius muscle on bothshins. Standing without vibration was tested first. Following one minutefor adaptation to the device 10, standing with shin vibration wastested. Each test lasted thirty seconds. During testing, subjects kepttheir eyes closed to exclude visual control of posture and limitpostural control to proprioceptive and vestibular systems.

Standing balance was evaluated using an FDA-approved device, BalanSENS(BioSensics, Watertown, Mass.). The subjects wore motion sensors 40(e.g., triaxial gyroscope sensors) on the right shin and on the waist(as shown in FIGS. 2A and 2B). Using these sensors 40, anterio-posteriorand medio-lateral angular deviations in the subject's ankle and hipjoints were measured. Position of the center of mass (COM) in thehorizontal plane and the range of movement thereof during a test wereestimated using the acquired ankle and hip angular deviations and abiomechanical model of the human body. Fall risk was determined using aSTEADI falls assessment score. To assess postural stability (i.e.,maintenance of balance) with and without proprioceptive vibration, arange of COM during vertical position (i.e., standing) was evaluated.Generally, a lower COM range indicates better balance.

During standing without shin vibration, in the YS group, the range ofCOM position varied among subjects from 0.19 to 1.6 cm², and on averagewas 0.65±0.33 cm², while in the OS group, the range of COM positionvaried among subjects in a wider range from 0.22 to 2.22 cm², and onaverage was 0.81±0.54 cm². When the device 10 was activated andproviding proprioceptive stimulation, the range of COM positionincreased in 8 (80%), and decreased in 2 (20%) of the YS group. Thus,with activation of the device 10, in the YS group, variability of rangeof COM position expanded from 0.2 to 4.08 cm² and on average increasedto 1.32±1.22 cm² (p=0.067, two-tailed t-test). However, the effect ofproprioceptive stimulation in the OS group was different: the range ofCOM position and movement increased in a smaller part of the group(7/19, 37%), but decreased in a larger part of the group (12/19, 63%).

These results generally illustrate that embodiments of the device 10 canprovide benefits to individuals that need assistance in maintainingbalance and preventing unintentional falls. More specifically, thedevice 10 may improve balance and reduce risk of unintentional falls inthose in need, such as older subjects, but may not be effective forthose who are at lesser risk, such as younger subjects.

To further illustrate this principle and to analyze postural responsesof the groups to proprioceptive stimulation, the relationship between achange in COM range (ΔCOM) during stimulation and COM range duringstanding without vibration was examined (as generally illustrated inFIG. 4A, with respect to the YS group, and 4B, with respect to the OSgroup). During proprioceptive stimulation, COM range tended to increasein subjects with an initial small COM range (e.g., those with betterbalance), but tended to decrease in subjects with an initial large COMrange during standing without proprioceptive stimulation (e.g., thosewith worse balance). For the OS group, as shown in FIG. 4B, therelationship between ΔCOM and COM range during standing withoutvibration was approximated with a linear regression line 42 having anegative slope (ΔCOM=−0.46*COM+0.28 (r=0.64)). The regression line 42intercepted the x-axis at COM range of 0.62 cm².

Noteworthy, the intercept value was almost identical to the average COMrange during standing without proprioceptive stimulation in YS.Furthermore, this interception divided the OS group in two subgroups:stable OS, with low COM range during standing without proprioceptivestimulation, and unstable OS, with large COM range during standingwithout proprioceptive stimulation. The subgroup of stable OS consistedof eight subjects. In six (75%) of the stable OS group, ΔCOM waspositive, and in two (25%) ΔCOM was negative during proprioceptivestimulation; also, six subjects of this subgroup did not have posturaldisturbances in the past, while two subjects experienced falls. Thesubgroup of unstable OS consisted of eleven subjects. In four (36%),ΔCOM was positive, and in seven (64%), ΔCOM was negative duringproprioceptive stimulation; also, three subjects (27%) of this subgroupdid not have postural disturbances in the past, but eight subjects (72%)experienced falls. A binomial distribution test showed that aprobability of a member of unstable OS subgroup to experience a fall was0.92. Proprioceptive stimulation using embodiments of the device 10could decrease COM range during standing in the unstable OS subgroup,and shift it toward the COM range of stable subjects. The results ofthis experimental study indicate that low frequency proprioceptivestimulation may increase postural stability during standing in those athigh fall risk, and has the potential to reduce the risk of falls, butmay not significantly benefit young subjects and elders with unimpairedbalance.

According to another study, postural stability was examined in thirtysubjects divided into three groups: healthy young subjects (HY, 10subjects, five males and five females (23.3±2.3 years)), healthy elderlypersons (HE, 10 subjects, three males and seven females (72.9±2.8years)), and elderly persons at high risk of fall (FR, 10 subjects with3±4.6 falls within one year, three males and seven females (83.6±9.6years)).

The same device 10 and general methods described above were used in thisstudy. To assess postural stability of the subjects (i.e., maintenanceof balance) with and without proprioceptive vibration, COM displacementsduring vertical position (i.e., standing) with eyes closed wereevaluated. Balance parameters in the three groups of subjects werecompared using ANOVA and post-hoc Tukey HSD test.

FIGS. 5A-5F illustrate differences in COM sway with and without 30 Hzproprioceptive vibration. More specifically, FIGS. 5A, 5B, and 5C arebar graphs illustrating average COM sway without vibration 50 and with30 Hz proprioceptive vibration 52 for the HY group, the HE group, andthe FR group, respectively. FIGS. 5D, 5E, and 5F are graphs illustratingCOM sway during proprioceptive vibration as a function of baseline(i.e., no vibration) COM sway for the HY group, the HE group, and the FRgroup, respectively. Additionally, Table 1 below illustrates differencesin assessed parameters (COM anterio-posterior (AP), COM medio-lateral(ML), and COM sway) before and during vibration using repeated measuresMANOVA. Differences in frequencies of parameter increases (+) anddecreases (−) that occurred during vibration were assessed using χ²test. Within Table 1, statistically significant differences between thebalance parameter in two conditions (p<0.05) are indicated by a singlestar (*), while differences between the balance parameter that are justabove statistical significance (0.1<p<0.05) are indicated by two stars(**).

TABLE 1 COM displacements and sway in persons standing with eyes closedbefore and during 30 Hz shin vibration. Fall Risk Group Healthy YoungHealthy Elderly Elderly difference COM AP (cm) Before vibration 1.21 ±1.08 1.12 ± 0.45 1.68 ± 0.64 F(2, 9) = 3.43, During vibration 1.55 ±0.89 1.25 ± 0.63 1.39 ± 0.47 p = 0.0472* F(1, 9) = 1.63, F(1, 9) = 0.25,F(1, 9) = 19.43, p = 0.2338 p = 0.6268 p = 0.0017* (+) 7 (−) 3 (+) 5 (−)5 (+) 0 (−) 10 p = 0.2059 p = 1.0 p = 0.0016* COM ML (cm) Beforevibration 1.21 ± 1.08 1.12 ± 0.45 1.68 ± 0.64 F(2, 9) = 3.24, Duringvibration 0.86 ± 0.19 0.73 ± 0.21 0.86 ± 0.24 p = 0.0550** F(1, 9) =2.34, F(1, 9) = 0.07, F(1, 9) = 5.31, p = 0.1607 p = 0.7941 p = 0.0467*(+) 8 (−) 2 (+) 5 (−) 5 (+) 2 (−) 8 p = 0.0568** p = 1.0 p = 0.0568**COM sway (cm{circumflex over ( )}2) Before vibration 0.86 ± 0.62 0.69 ±0.43 1.40 ± 0.96 F(2, 9) = 2.74, During vibration 1.32 ± 1.20 0.66 ±0.57 0.94 ± 0.47 p = 0.0822** F(1, 9) = 1.63, F(1, 9) = 0.02, F(1, 9) =6.47, p = 0.2340 p = 0.8861 p = 0.0316* (+) 6 (−) 4 (+) 3 (−) 7 (+) 2(−) 8 p = 0.5271 p = 0.2059 p = 0.0568**

As shown in Table 1, during standing without shin vibration, balanceparameters were similar in the two groups of healthy participants (HYand HE). At variance, participants of the FR group had a substantiallyhigher range of COM displacements during quiet standing. In the FRgroup, COM anterio-posterior (AP) displacements were significantlylarger, and COM medio-lateral (ML) displacements, as well as COM swaywere almost significantly larger than these parameters in both HY and HEgroups.

When the device 10 was active and vibrated shins, thus providingproprioceptive stimulation, only a few changes were seen in the balanceparameters in the HY and HE groups (as shown in Table 1 and FIGS. 5A,5B, 5D, and 5E). Only the HY group experienced a noticeable increase inCOM ML displacements. In contrast, statistically significant changes inbalance parameters occurred during shin vibration in the FR group, andCOM AP and ML displacements as well as COM sway decreased significantly(as shown in Table 1 and FIG. 5C). In particular, COM AP displacementsdecreased in 100% of participants of the FR group, while both COM MLdisplacements and COM sway decreased in 80% of participants of the FRgroup (as shown in Table 1 and FIG. 5F).

The results of this experimental study indicate that low frequencyproprioceptive stimulation can increase postural stability duringstanding for elders at high fall risk. Young subjects and elders withunimpaired balance are not significantly affected by such shinvibrations. The results illustrate that embodiments of the device 10have a potential to provide benefits to individuals that need assistancein maintaining balance while reducing the risk of unintentional fallswhile standing and walking. By way of example, someone with imperfectvision may wear glasses to correct their vision. However, those glasseswould have the opposite effect on someone with perfect or good visionand, instead, blur their vision. Similarly, here, the device 10 mayimprove balance in those who are in need, but may have no effect or aworsening effect for those who generally have good balance. In otherwords, such stimulation may disturb the function of a well-balancedneuromuscular system, but improve the function of a decliningneuromuscular system.

In light of the above, the embodiments of the disclosure provide adevice and methods to provide proprioceptive stimulation to relevantmuscle groups that may play a role in maintaining balance. As a result,the device and methods can help improve postural performance and reducea risk of loss of balance or unexpected falls for those in need.Moreover, the device comprises minimal parts and uses anatomy of theuser's body to control operation. This simple operation (e.g., providinga sensor that turns vibration on and off based on user orientation) canincrease reliability compared to more complex devices and can providethe above benefits at a relatively low cost to the user, which isdesirable because of rising medical expenses for the elderly.Additionally, by providing vibrational stimulation, the device can beconsidered non-invasive and, by failing to induce muscle contractions,the device generally will not cause the user the physical andpsychological discomfort of ongoing muscle contractions.

It should be understood from the foregoing that, while particularembodiments have been illustrated and described, various modificationscan be made thereto without departing from the spirit and scope of theinvention as will be apparent to those skilled in the art. Such changesand modifications are within the scope and teachings of this inventionas defined in the claims appended hereto. Also, throughout thedisclosure, the term “about” means a range of plus or minus 20% withrespect to the specified value, more preferably plus or minus 10%, evenmore preferably plus or minus 5%, most preferably plus or minus 2%. Inthe alternative, as known in the art, the term “about” indicates adeviation, from the specified value, that is equal to half of a minimumincrement of a measure available during the process of measurement ofsuch value with a given measurement tool.

All references contained herein are hereby incorporated by reference forany and all purposes of supporting the instant specification, includingthe following: Ambrose A F, Paul G, Hausdorff J M. Risk factors forfalls among older adults: A review of the literature. Maturitas 2013;75: 51-61; Iliopoulos F, Nierhaus T, Villringer A. Electrical noisemodulates perception of electrical pulses in humans: sensationenhancement via stochastic resonance. Journal of Neurophysiology 2014;111: 1238-48; Gravelle D C, Laughton C A, Dhruv N T, et al.Noise-enhanced balance control in older adults Neuroreport 2002; 13:1853-6; Priplata A A, Niemi J B, Harry J D, Lipsitz L A, Collins J J.Vibrating insoles and balance control in elderly people. Lancet 2003;362: 1123-4; Horak F B, Nashner L M. Central programming of posturalmovements: adaptation to altered support-surface configurations. Journalof Neurophysiology 1986; 55: 1369-81; Cordo P, Inglis J T, VerschuerenS, et al. Noise in human muscle spindles Nature 1996; 383: 769-70;Martinez L, Perez T, Mirasso C R, Manjarrez E. Stochastic resonance inthe motor system: Effects of noise on the monosynaptic reflex pathway ofthe cat spinal cord. Journal of Neurophysiology 2007; 97: 4007-16.

What is claimed is:
 1. A method of reducing a risk of unintentionalfalls in a user, the method comprising the steps of: providing a deviceconfigured to be worn by the user, the device comprising: a stimulatorconfigured to be positioned adjacent a body portion of the user, and asensor configured to be positioned adjacent to an upper leg of the user,the sensor configured to be in communication with the stimulator and toprovide an activation signal when the user is in a substantiallystanding position; donning the device by the user; and activating thestimulator via the activation signal from the sensor when the user is inthe substantially standing position, wherein activating the stimulatorincludes causing the stimulator to vibrate against the body portion ofthe user at a frequency that stimulates proprioceptors of the user. 2.The method of claim 1 and further comprising deactivating the stimulatorvia the sensor when the user is in a substantially seated position. 3.The method of claim 1, wherein the frequency is less than 40 Hz.
 4. Themethod of claim 1, wherein the frequency is one of about 30 Hz, about 20Hz, and about 10 Hz.
 5. The method of claim 1, wherein donning thedevice by the user includes positioning the stimulator adjacent one of acalf of the user and a lower back of the user.
 6. A device for providingproprioceptive stimulation to a user, the device comprising: a sensorconfigured to be positioned adjacent a body portion of the user thatchanges orientation when the user sits and stands, the sensor configuredto emit an activation signal when the user stands and to emit adeactivation signal when the user sits or lies down; and a stimulator incommunication with the sensor and configured to be positioned adjacentone of a calf and a lower back of the user, the stimulator configured tovibrate at a frequency that stimulates proprioceptors of the userwithout inducing muscle contractions upon receipt of the activationsignal from the sensor and to cease vibration upon receipt of thedeactivation signal from the sensor.